Generally, a hydraulic excavator, a typical example of a construction machine, is roughly configured with a mobile lower traveling body, an upper swivel body mounted on the lower traveling body so as to be able to swivel freely, and a working arm device connected to the upper swivel body so as to be able to move up and down freely. The upper swivel body has a swiveling frame configuring the framing structure thereof, and the swiveling frame is provided with a cab in which an operator rides, an equipment room where various equipment such as an engine and radiator are stored, a counterweight for balancing the weight of a load with respect to the working arm device, and the like.
Most of these hydraulic excavators are usually equipped with an air conditioner for a cab which is configured with an exterior unit disposed outside the cab and an interior unit disposed inside the cab. The exterior unit has a compressor for compressing a refrigerant, a condenser for condensing the refrigerant compressed by the compressor, and a receiver for storing the refrigerant condensed by the condenser. The interior unit, on the other hand, has an expansion valve that expands the refrigerant transferred from the receiver, and an evaporator that evaporates the refrigerant expanded by the expansion valve.
The receiver of the exterior unit and the expansion valve of the interior unit are connected to each other by a supply pipe, so that the refrigerant for cooling the inside is supplied from the receiver of the exterior unit to the expansion valve of the interior unit through the supply pipe. The expansion valve of the interior unit and the compressor of the exterior unit are connected to each other by a discharge pipe, so that the refrigerant circulates between the interior unit and the exterior unit (see Patent Literature 1, for example).
Japanese Patent Application Laid-open No. 2009-274462